Google DoubleClick

Google acquired the DoubleClick banner advertisement business in 2007 for $3.1 billion.

They acquired the revenues from DoubleClick, but also a massive amount of internet traffic share. The acquisition was controversial, due to various antitrust concerns, as well as privacy concerns surrounding DoubleClick's ad-serving methodologies.

• Acquisition story on BusinessWeek
• Read more about DoubleClick on Wikipedia